ABSTRACT
The effects of isotopic composition and disorder on the properties of semiconductors have been the subject of numerous recent studies, as detailed in several reviews[1-5]. Isotopically purified Ge and C (diamond) were the first such semiconductors to become available in the form of bulk single crystals of reasonable purity, allowing for the investigation of isotope effects on thermal conductivity, phonon energies and broadenings, and direct and indirect electronic band gaps[l4]. Until our recent studies [6 -8], the chemical purity of isotopically enriched Si was not sufficient to allow for photoluminescence (PL) spectroscopy. In this talk we summarize the results of our recent publications, and provide PL spectra of new, improved samples, which demonstrate some of the interesting effects even more clearly. The reader is referred to these previous publications [6 -8] for more complete references to related earlier work, both in Si as well as in other semiconductors.
